For continuous molten metal casting, using steel as an example, the molten metal is tapped via a bottom tapping hole from a molten metal container above a continuous casting mold, the latter having an open top and bottom and being designed so that the molten metal in contact with the mold solidifies to form a solid metal skin retaining unsolified molten metal and forming a strand which continuously travels from the bottom of the mold. The traveling strand ordinarily retains molten metal which gradually solidifies to form an entirely solid metal strand.
To prevent the molten metal from solidifying under static conditions within the skin, and forming an undesirable crystalline structure, it is possible to inductively stir the molten metal within the strand leaving the mold. Ordinarily this cannot be done very close to the mold and heretofore it has not been possible to stir the molten metal within the skin forming on the inside of the mold. The metal solidifying inside of the mold does not obtain the advantages of stirring.
Continuous casting molds are made of copper or at least incorporate a substantial amount of copper in their construction because the high heat conductivity of copper facilitates the removal of heat required for the continuously casting strand to travel from the mold without involving a serious risk of a molten metal breakout through the skin. For this reason it is impractical to attempt to inductively stir the molten metal within the continuous casting mold.
However, it would be desirable to stir the molten metal during its passage through the mold while the skin is initially forming.